Detonator plug manufacture



Dec. 20, 1960 H. E. HAY

DETONATOR PLUG MANUFACTURE Filed July 20. 1955 HORACE E. H

ENTO

Unite States 2,964,835 DETONATOR PLUG MANUFACTURE Horace E. Hay, Athens, Ala., assignor to Atlas Powder Company, Wilmington, DeL, a corporation of Delaware The present invention relates to improvements in methods for manufacturing electric detonator plugs of the type in which a central electrically conductive pin is insulated from a surrounding conducting sleeve.

The invention can be generally described as fellows: A central pin having a broad portion is driven into a sleeve which has an inside diameter larger than the unbroadened portion of the pin, but smaller than the broadened portion of the pin. Dielectric bonding material is forced into the open space between the sleeve and the pin. Then the portion of the assembly where the broad portion of the pin touches the sleeve is removed by a transverse cut through the assembly. There is left a plug assembly which includes a sleeve and a central core separated by dielectric bonding material. A bridge wire may then be connected across the one end between the sleeve and the core, or the plug may be directly in cluded in a detonator assembly so that a spark sensitive ignition composition is located across the end between the core and annular sleeve.

The invention will be further described in connection with the accompanying dnawings, which show one specific preferred embodiment, and in which:

Figure l is a disassembled view, partly in section, of a pin and sleeve of the invention prior to assembly.

Figure 2 is a disassembled sectional view of the pin, broadened on one end, ready for insertion into the sleeve and with the sleeve seated in a holder.

Figure 3 is a top view of the arrangement shown in Figure 2.

Figure 4 is a view like Figure 2 but with the pin inserted in the sleeve.

Figure 5 is a top view of Figure 4.

Figure 6 is a sectional view of the sleeve and pin shown in Figure 4 having insulating material extruded into the space between pin and sleeve.

Figure 7 is a sectional view of the completed detonator plug.

Figure 8 is a sectional view of a completed detonator containing the plug shown in Figure 7.

Referring now to Figure 1 of the drawings, 11 is a metal pin which is intended to be the central pole or terminal of a detonator plug of the invention. 13 is a metal sleeve which is intended to be the other pole of the detonator plug of the invention. Pin 11 is smaller in diameter than is the bore of sleeve 13. As shown, sleeve 13 is provided with a shoulder 15, which is not necessary to the invention but which is useful in assembling the plug into some detonator devices.

Figure 2 shows a step in assembling the plug of the invention. As there shown, pin 11 has been provided with a flattened end portion 17. This may be conveniently done by swaging one end of the pin with a hammer. Swaged end 17 is sufiiciently broad to provide a tight fit in sleeve 13. As is also shown in Figure 2, sleeve 13 is seated in a base or holder member 19 which includes collar portion 21 in which shoulder 15 of sleeve 13 seats.

atent Base 19 is provided under the bore of sleeve 13 with a recess 23.

Pin 11 is driven into the bore'of sleeve 13 until pin 11 extends into recess 23. (See Figure 4.) Syvaged end 17 of pin 11 then fits tightly into the bore of sleeve 13. It is desirable that swaged end 17 be suificiently broad that sleeve 13 is slightly deformed by it to an oval form as shown in Figure 5. It has been found that when sleeve 13 is so deformed as'pin 11 is driven through it, the action of swaged portion 17 in pushing against the side walls of sleeve 13 is such that pin 11 is centered in the bore of sleeve 13. The centering of pin 11 is assisted by pushing it sufiiciently far into the bore of sleeve 13 a that its rounded end portion 25 fits into recess 23.

The sleeve and pin assembly which appears in Figures 4 and 5 is then seated in the mouth of an extrusion gun generally shown at 27. Extrusion gun 27 forms no part of the preseht invention. It is merely shown generally for illustrative purposes. Through the medium of extrusion gun 27, or by any other convenient means, dielectric bonding compound 28 is inserted into the annular space between pin 11 and sleeve 13. Various dielectric bonding compositions may be used, as for example, tar, rubber base cements, epoxy resins or other plastic compositions, or porcelain cement or other compositions which may be fired. After the annulus between pin 11 and sleeve 13 has been filled with insulating composition, the portion of the assembly containing the swaged end 17 of pin 11 is cut oif at the point indicated by line 77 of Figure 6. If the dielectric bonding composition 28 requires it, the resulting product may then be fired.

A final plug assembly is shown in Figure 7, a bridge wire 29, in this case, having been welded between pin 11 and sleeve 13.

Figure 8 shows a completed detonator made with the plug shown in Figure 7. A flash composition 33 is painted or dipped as a button onto bridge wire 29. A detonating explosive 35 is loaded into shell 31, and the shell 31 is crimped around the plug. Pin 11 and sleeve 13 may then be used as terminals for electrical initiation of the detonator.

A loose flash composition may be disposed about the bridge wire instead of the painted or dipped button 33 shown. Also, as pointed out above, bridge wire 29 may be dispensed with and a spark sensitive composition located across the gap between core 11 and sleeve 13.

What is claimed is:

1. A method of making a detonator plug, of the type comprising a conductive pin surrounded by an annular conductive sleeve and separated therefrom by dielectric bonding material, which comprises providing said pin with a broad portion, said broad portion having a transverse dimension somewhat larger than the inside diameter of said sleeve and having a tapered relationship with the inside of said sleeve toward the unbroadened portion of said pin, forcing said pin and broad portion into the bore of said sleeve so that said pin, through the medium of said broad portion, fits tightly in said sleeve, the unbroadened portion of said pin being centered in said sleevemember and withheld from contact therewith by the contact between the broad portion of the said pin and the said sleeve member interposing dielectric bonding material between said sleeve and said centered pin so as to bond said sleeve to said pin, and cutting said assembly transversely so as to remove the portion of said assembly where said broad portion touches said sleeve.

2. A method according to claim 1 in which said pin is swaged to produce said broad portion.

3. A method according to claim 1 in which said broad portion of said pin deforms said sleeve as it fits into it.

4. A method of forming a detonator plug of the type whichincludes a conductive .outter sleeve aflconduct'ive p'iri aligned'on the longitudinal axis of said sleeve and a dielectric bonding material within the annulus between said pin and said sleeve which comprises the steps of: broa en g one end of said pin so that it ha a ran verse dimension slightly larger than the internal e r ofsaid sleeve and tapers to the diameter of said pin,

inserting said pin-into said sleeve 50 that i1 is longitlle dinally cen e ed nd h -enl rge po ion frioti na l thesteps of: swaging one end of said pin so that its transverse dimension is slightly larger than theinternal diameter of said sleeve and'so that a symmetrically tapered head is produced, inserting said pin into'said' sleeve until said sleeve forms" a detent for said head retaining said pin in fixed centered position, filling the annulus between said sleeve and said pin with a dielectric bonding material so as to bond said sleeve to said pin,

' and severing the portion of the assembly which contains the enlarged portion of said pin. V

Referenees Cited in the file of this patent UNITED STATES; P,AII" EI I',I' S

2,530,934. 1 Barton et a1. Nov. 21, 1950 2,687,667 Gunther Aug. 31, 1954 2,732,614 Shower Jan. 31, 1956 2,781,308 Crelrtz et al Feb. 12, 1957 2,796,458 Hartmann June '18, 1957 FOREIGN PATENTS France June 14, 1932 

